Unable to read a file and pass into arguments - c

Question

1) I'm trying to open a file, read the mix data (ints, chars and strings) and store them into args.
1.1) so in the sample.txt is a total of 13 (excluding args[0])
2) Need to read a file from terminal "./myprog.c < sample.txt"
Heres my code and have no idea where i went wrong:
sample.txt:
123 213 110 90 1
hello my friend
boo bleh
a b c
myprog.c:
#include <stdio.h>
int main()
{
int i = 1;
FILE *fstin=fopen(argv[0], "r"); //open the file
if (fstin == NULL) {
puts("Couldn't fopen...");
return -1;
}
//Getting all the inputs from file
while ((fscanf(fstin, "%d", argv[i])) != EOF){
i++;
}
fclose(fstin);
for (i=0; i<10; i++) {
printf("%d\n",argv[i]);
}
return 0;
}
Any help is greatly appreciated!
PS: Would like if anyone could post their complete solution? Will upload unto this post and let everyone have a review of this problem
PPS: Please excuse the poor level of coding as I am a beginner and completely new to C.

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int ac, char *av[]){
int i, argc=0;
char **argv=NULL, data[16];
FILE *fstin = stdin;
if(ac == 2){
if(NULL==(fstin = fopen(av[1], "r"))){
puts("Couldn't fopen...");
return -1;
}
}
while (1==fscanf(fstin, "%15s", data)){
argv = realloc(argv, (argc+1)*sizeof(char*));
argv[argc] = malloc(strlen(data)+1);
strcpy(argv[argc++], data);
}
if(ac == 2)
fclose(fstin);
for (i=0; i<argc; ++i) {
printf("%s\n", argv[i]);
}
//deallocate
return 0;
}

Answer 2

You are making mistake at 2nd point where you divert your file to other file which is wrong. Actually you need to first compile and need to make executable.
gcc -o my_prog ./myprog.c -Wall
You need to execute this program as below to read file from c program:
./my_prog ./sample.txt
As you are new to C programming first go to man pages related to file operations.
Solution:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char *argv[]) {
//If command line argument is not inserted then stop operation
if (2 != argc) {
printf("Invalid number of arguments : %d\n", argc);
return -1;
}
int size = 0, ret = 0;
char *data = NULL;
FILE *fp = NULL;
//Open file in read mode given from command line argument
if (NULL != (fp = fopen(argv[1], "r")))
{
//Find size of file
fseek(fp, 0L, SEEK_END);
size = ftell(fp);
fseek(fp, 0L, SEEK_SET);
//if file is empty no need to read it.
if (size > 0)
{
//Data pointer which contains file information
data = (char *) calloc(sizeof(char), size);
if (NULL != data)
{
//Read whole file in one statement
fread(data, sizeof(char), size, fp);
printf("File %s is readed successfully\n", argv[1]);
printf("Data:\n");
printf("%s\n", data);
free(data); data = NULL;
}
else
{
perror("memory allocation failed\n");
ret = -1;
}
}
else
{
printf("File %s is empty\n", argv[1]);
}
fclose(fp); fp = NULL;
}
else
{
perror("File open failed\n");
ret = -1;
}
return ret;
}
Now Test it on your setup and if any query please post comments.